Nice attack: 84 confirmed dead after lorry crashes into crowd at Bastille Day celebrations in France

Witnesses say driver jumped out of lorry filled with grenades and guns and began shooting at people

Terror has again hit the streets of France after a lorry was driven, seemingly deliberately, into a large crowd of people celebrating Bastille Day on the seafront in Nice, France.

At least 84 people have been killed, including a number of children, and more than a dozen remained were critically injured, according to the latest count from the French interior ministry. The driver of the truck, identified in French media as a 31-year-old local of Tunisian origin, is understood to have been shot dead by police at the scene.

Many hundreds were told to run from the scene by police, and the president of the local region, Christian Estrosi, urged everyone in the city to remain indoors.

Witnesses said the driver hit the crowd at high speed, swerving to hit as many as possible before climbing out of the car and shooting more dead.

Mr Estrosi said the lorry was loaded with grenades and guns.

He said "every heart" was with them: "We must stand firm. Proud of the solidarity which is being organised in Nice".

President Francois Hollande rushed back to Paris in the wake of the attack, and announced three security measures, including the extension of France's state of emergency - due to end on 26 July - for a further three months.

"A horror has come down on France again," he said, adding that "the terrorist character [of the the attack] cannot be denied".

The attack happened on the Promenade des Anglais at around 10:30pm local time at the end of a firework display in what local officials are treating as serious terror attack.

Amid rumours of a hostage situation at a hotel in the city and of an accomplice inside the truck itself, police said they are working to establish if the driver was "working alone".

Images emerged of the badly damaged truck, its windscreen riddled with bullets. Witnesses say there was an exchange of gunfire between the driver and police.

Anti-terror investigators have taken over the scene which has been cordoned off to the public, and an anti-terror probe has now officially been opened.

A spokesman for France's interior ministry said there is going to be "a very high death toll".

One witness, Colin Srivastava, said: "The police told us run, now!"

Another, Roy Calley, told the BBC shots between the driver and police were fired as soon as they began to approach.

A student at the celebration told local newspaper Nice Matin: "We were at Neptune Beach and the fireworks ended so we started to head back.

"At that moment we saw the white lorry. It was around six tonnes and going at around 60-70km per hour.

"I saw behind the wheel. The driver was decided on where he was going. It happened two metres from us. I saw people lying, I saw a child on the ground".

A paramedic attends one of the dozens of people injured in the Nice Bastille Day attack (Reuters)

Facebook has activated its security check service for people in the area to let people inform there families and friends.

People on social media are using the hashtag #PortesOuvertesNice (Doors Open Nice) to help visitors stranded in the city after local authorities told people to remain inside.

One image on Twitter shows dozens of people lying injured on the floor with another showing a white lorry stopped in the middle of the street with four police officers observing it from a nearby palm tree.

Soldiers march on street where the lorry crashed into the crowd - possibly killing as many as 30 people (Reuters)

The British Foreign Office has said it is contacting local authorities to help any British citizens in the city.

A No 10 spokesman said Theresa May is being kept informed about the situation and has expressed her condolences to the victims' families.

Republican US presidential nominee Donald Trump has cancelled his news conference on Friday in light of the attack.

President Barack Obama has released a statement condemning the attack

Mr Hollande expressed solidarity with the victims of the attack, while sounding a defiant note, saying France would continue its operations in Syria and Iraq.

"After Paris, Nice is now hit," he said. "It is all of France which is under threat of Islamic terrorism.

"It is clear we need to do all we can to fight against terrorism," he said. "France is strong, and France will always be stronger, I assure you."